In the field of fiber-optic bidirectional communications, transceiver modules for optical communications are used. The transceiver module for optical communications is constructed by containing an optical transmitter and receiver circuit equipped with a light-emitting device such as an LD (laser diode) or a light-receiving device such as a PD (photodiode) in a compact package. The transceiver module for optical communications further includes an optical receptacle section attached to the casing of the compact package. By connecting an optical fiber to the optical receptacle section, communication between the transceiver module for optical communications and a counterpart transceiver module for optical communications is performed.
A schematic cross section of a conventional transceiver module for optical communications is shown in FIG. 7. The conventional transceiver module for optical communications 50 is composed of an optical receptacle 30 and an optical device unit 40.
The optical device unit 40 includes an optical device 41, which is a light-emitting device such as an LD or a light-receiving device such as a PD, stored in a casing composed of a device holder 42 and a device cover 43. The optical device unit 40 is secured, via a centering adapter 44, to a holder 37 of the optical receptacle 30.
The optical receptacle 30 comprises a fiber stub 34, a sleeve 35, a sleeve case 36, and a holder 37. An optical fiber is inserted into the fiber stub 34 so as to be located in a position corresponding to the center axis of the fiber stub 34. The holder 37 retains the fiber stub 34 therein, and covers the outer periphery of a lower part of the sleeve 35 for supporting the sleeve 35. The sleeve case 36 is secured to the holder 37 so as to cover the sleeve 35.
When an optical connector is connected to the optical receptacle 30, a ferrule disposed within the optical connector is guided by the sleeve 35 to cause the front end face of the ferrule to abut on the front end face of the fiber stub 34 in axial alignment with each other. This enables an optical fiber in the ferrule to abut on an optical fiber in the fiber stub 34, thus achieving optical signal connection.
The sleeve case 36 of the optical receptacle 30 is constructed of a resin molded product. The sleeve case 36 has a slim slit-like engagement hole 36a formed at a lower part thereof so as to extend circumferentially. On the other hand, the holder 37 has an engagement pawl 37a to hook in the engagement hole 36a. The sleeve case 36 is fastened to the holder 37 by pushing the sleeve case 36 into the holder 37 to effect an engagement between the engagement hole 36a and the engagement pawl 37a. 
In the optical receptacle 30, since the sleeve case 36 is made of resin, the sleeve case 36 does not act as an antenna to receive noise. Moreover, the optical receptacle 30 can be produced at lower costs and assembled with ease.